The chemolithoautotroph Acidithiobacillus ferrooxidans can survive under phosphate-limiting conditions by expressing a C-P lyase operon that allows it to grow on phosphonates
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2008-03Metadata
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Vera, Mario
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The chemolithoautotroph Acidithiobacillus ferrooxidans can survive under phosphate-limiting conditions by expressing a C-P lyase operon that allows it to grow on phosphonates
Abstract
The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans is of great importance in biomining
operations. During the bioleaching of ores, microorganisms are subjected to a variety of environmental stresses
and to the limitations of some nutrients, such as inorganic phosphate (Pi), which is an essential component for
all living cells. Although the primary source of phosphorus for microorganisms is Pi, some bacteria are also
able to metabolize Pi esters (with a C-O-P bond) and phosphonates (with a very inert C-P bond). By using
bioinformatic analysis of genomic sequences of the type strain of A. ferrooxidans (ATCC 23270), we found that
as part of a Pho regulon, this bacterium has a complete gene cluster encoding C-P lyase, which is the main
bacterial enzyme involved in phosphonate (Pn) degradation in other microorganisms. A. ferrooxidans was able
to grow in the presence of methyl-Pn or ethyl-Pn as an alternative phosphorus source. Under these growth
conditions, a great reduction in inorganic polyphosphate (polyP) levels was seen compared with the level for
cells grown in the presence of Pi. By means of reverse transcription-PCR (RT-PCR), DNA macroarrays, and
real-time RT-PCR experiments, it was found that A. ferrooxidans phn genes were cotranscribed and their
expression was induced when the microorganism was grown in methyl-Pn as the only phosphorus source. This
is the first report of phosphonate utilization in a chemolithoautotrophic microorganism. The existence of a
functional C-P lyase system is a clear advantage for the survival under Pi limitation, a condition that may
greatly affect the bioleaching of ores.
Patrocinador
This work was supported by ICM P-05-001-F project and doctoral
fellowships from CONICYT, ICM, and the Maria Ghilardi Venegas
Foundation to M.V.
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APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Volume: 74, Issue: 6, Pages: 1829-1835, 2008
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